Power-Efficient Gm-C Band-Pass Filter for Bio-Signal Acquisition

This paper presents a power-efficient, wide dynamic range, second-order tunable G_m-C band-pass filter tailored for low-power biomedical signal processing. The design exploits MOS transistors operating in the subthreshold region to minimize power consumption. To enhance dynamic range, capacitive attenuation and bump linearization techniques are employed, while a Gyrator-C active inductor is integrated to improve the quality factor. The filter provides a tunable frequency range from 6.8 Hz to 707 Hz, suitable for physiological signals with a quality factor of 3 and a 2 dB gain. It achieves ultra-low power consumption between 4.4 nW and 234 nW, a dynamic range of 90.3 dB at 5% total harmonic distortion, and an input-referred noise below 30 μV_rms. The design occupies a silicon area of 0.1 mm² in a standard 0.18 μm CMOS process with a 1.8 V supply.